Known exchanging devices are so configured that, after each exchange, the taken-up component is reproducibly accommodated on the apparatus so that no new calibration of the taken-up component is needed and the measurement values, which are recorded with different sensors or different probe pins, can be combined with each other without a calibration being switched in therebetween.
Exchanging devices for coordinate measuring apparatus or processing machines are disclosed, for example, in U.S. Pat. Nos. 4,637,119; 4,649,623; 4,688,307; 5,041,806; 4,651,405; 4,738,033; 5,228,205; and, 4,254,554.
Exchanging devices are disclosed in U.S. Pat. Nos. 4,637,119; 4,649,623; 4,688,307; and, 5,041,806. In these exchanging devices, the clamping of the component to be accommodated on the take-up holder is done with magnetic force. In the arrangement described in U.S. Pat. No. 5,228,205, the clamping of the component to be taken up on the take-up holder is achieved with an underpressure vacuum bell and, in the arrangements of U.S. Pat. Nos. 4,651,405 and 4,738,033, the clamping takes place in each case mechanically. The magnetic clamping of the component to be taken up as set forth in U.S. Pat. Nos. 4,637,119; 4,649,623; 4,688,307; and, 5,041,806 as well as the take-up by suction of the component to be taken up in accordance with U.S. Pat. No. 5,228,205 are especially suited for automatic exchanging devices wherein the machine computer controls the component, which is to be exchanged, for example, dropping off the sensor to be exchanged in a magazine and taking up a new sensor from the magazine without the operator having to intervene in the exchange operation. If, however, the throwing off of the sensor or of the other taken up component is unintentionally triggered without having moved first to the magazine, then it can easily lead to unintended damage of the sensor when this sensor is dropped off at a higher elevation and falls down. For this reason, it is, for example, known to combine the magnetic clamping with a mechanical latch in rotation-pivot units. For the removal of the taken-up sensor or the taken-up rotation-pivot unit, the latch must be released either manually or is automatically released when dropping the rotation-pivot unit or the sensor in the magazine. The latch unit ensures a rigid coupling between the take-up component and the machine. However, in the case of an unintended collision during a measurement operation, in order to avoid excessive damage by the rigid coupling of the latch unit, the latch is so designed that it automatically unlatches when exceeding a specific force. In the case of a collision, it can happen that the taken-up sensor drops off and is damaged by the subsequent impact.
In the arrangement of U.S. Pat. No. 4,254,554, the component, which is to be taken up, is pulled by a pretensioned steel line against the three point bearing which ensures a reproducible taking up of the component to be taken up. This arrangement affords the advantage that, in the case of a collision, the component, which is to be taken up, can be lifted out of the bearing without the component, which is to be taken up, being entirely separated from the machine thereby. This arrangement is, however, not suitable for a manual or automated exchange.